

DEC 6 1897 



Gape Worm of Fowls 

( Syngamus trachealis); 



THE BARTHVSTORM 

(Lumbricus terrestris), 

ITS INTERMEDIATE HOST. 



ALSO, 

On the Prevention of the Disease in 

Fowls called the Gapes, which 

is Caused by this Parasite. 



BY • 
M. r>. WAIvKER, M. O., 

FRANKL1NVILLE, N. Y. 



TH E 



Gape Worm of Fowls 

{Synga.rn.us trachealis); 

THE KARTHWORM 

{Lumbricus terrestris), 
ITS INTERMEDIATE HOST. 

ALSO, 

On the Prevention of the Disease in Fowls 

Called the Gapes, which is Caused 

by this Parasite. 



By H. D. WALKER, M. D., 

FRANKLINVILLE, N. Y. 



COPYRIGHTED BY 

DR. H. D. WALKER. Franklinville, N. Y., 

AND 

J. Y. BICKNELL, Buffalo, N. Y. 
1897. 



1286 



SYNGAMUS TRACHEALIS. 

EXPLANATION OF FIGURES. 

Fig. 1. — Adult, male and female Syngamus, united (natural size and enlarged 12 diameters). 
A, male; B, female, each showing the head, esophagus and intestine. In the female 
may be seen the uterus and ovarian tubes filled with eggs. In the male, the semeniferous 
tube. 

Fig. 2. — Smallest pair of Syngami ever seen (enlarged 50 diameters). A, male; B, female. 

Fig. 3. — Embryo of Syngamus removed from the earthworm and kept in the blood serum of 
a calf, in an incubator, at 105° Fahr., between four and five days. About moulting the 
second time after being placed in the serum. Embryo lying within the exuviae. See 
structure of mouth of embryo, and also in the exuviae (enlarged 200 diameters). 

Fig. 4. — Embryo of Syngamus removed from the earthworm and kept in the blood serum of 
a calf, in an incubator, at 105° Fahr., for 24 hours. About moulting the first time after 
being placed in the serum (enlarged 200 diameters). 

Fig. 5. — Embryo of Syngamus removed from the lung of a chick fed earthworms containing 
the embryos. This embryo had just entered the lung (enlarged 200 diameters). 

Fig. 6. — Embryo of Syngamus removed from the intestinal canal of an earthworm (enlarged 
200 diameters). 

Fig. 7. — Embryo of Syngamus within the egg f enlarged 200 diameters). 

Fig. 8. — Egg of Syngamus in the mulberry state (enlarged 200 diameters). 

Fig. 9. — Perfect egg of Syngamus immediately after passing out of adult female (enlarged 
200 diameters). 

Fig. 10. — Caudal pouch of male. Observe the eight principal ribs which are subdivided so 
there are eighteen divisions at the circumference, each extremity of which is expanded 
into a sucker. These suckers project through the broad margin of the pouch which is 
closely applied around the vulva of the female, to which they enable it very firmly to 
adhere. The posterior part of the circumference of the pouch is cut out and has no suck- 
ers. Here is where the eggs pass out. 



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PREFACE. 

Fourteen years having- elapsed since I first commenced the 
study of the gapes in fowls, it cannot be asserted that the con- 
clusions now arrived at are hasty and have not stood the test 
of time and mature consideration. My first paper on the sub- 
ject was read before the Buffalo Microscopical Club, November 
nth, 1884. In 1886 I published a paper in the Bulletin of the 
Buffalo Society of Natural Sciences, Vol. V., No. 2. The pres- 
ent publication is a revision of that paper, with extracts from 
articles written for various journals, and additional matter here- 
tofore unpublished in regard to the life history of the parasite 
causing the gapes. The illustrations are from drawings made 
by Mrs. Helen M. Judd from microscopic slides. I send forth 
this small pamphlet with the earnest desire that science and the 
poultry and game bird raisers throughout the world may be 

benefitted thereby. 

H. D. WALKER. 
Franklinville, N. Y., November, 1897. 



INTRODUCTION. 

In the following- pages we present the results of experiments 
made for the purpose of determining the intermediate host of 
the gape worm of fowls. We have endeavored at the same time 
to trace out the life history of this parasite, in its various stages 
from the egg to the perfect worm, also to devise means for the 
prevention of the disease caused by it among fowls. 

The object of undertaking the work was two-fold. First, it 
was thought if its intermediate host could be discovered the 
disease might be prevented to a great degree, and much good 
result therefrom. Second, the love of original investigation and 
a determination to work out the life history of this parasite, 
which, although well known in its mature condition in the 
trachea of fowls for about one hundred years, had thus far, in its 
embryonic state in nature, remained unknown. The work has 
been exceedingly difficult, for several reasons. When the inves- 
tigation was begun, I knew nothing about Entozoa. Microscop- 
ical work was also comparatively new. Living in a small vil- 
lage, I had no public libraries to consult, and was dependent for 
the literature of the Entozoa on a few books which I procured 
during the investigation. My profession also left me little leisure, 
and the most of this work has been done at such odd times as I 
could spare from other duties. I wish here to express my thanks 
to that eminent naturalist, the late Dr. Joseph Leidy, of Phila- 
delphia, for many favors in inspecting my microscopic slides, and 
for advice and encouragement in the work. Valuable, indeed, 
were the services he rendered me. I am under obligations to 
Lord Walsingham, of England, for books to aid in the investi- 
gation. Friends in the Buffalo Microscopical Club, and neigh- 
bors have also assisted me in various ways. I have freely con- 
sulted Dr. T. Spencer Cobbold's work on "Parasites," also Pro- 
fessor L. G. Neumann's treatise on "Parasites and Parasitic Dis- 
eases of Domesticated Animals," and Dr. Pierre Megnin, "On 
the Gapes Disease in Gallinaceous Birds." Finally, I trust these 
pages will not be scanned with too critical an eye, for, doubtless, 
imperfections will be found. I can only say that I have honestly 
endeavored, according to the best of my ability, to place before 
the reader the life history of one of the humblest of creatures, a 
worm, but which, nevertheless, plays well its own part in this 
world of animated nature. 



ZOOLOGICAL CLASSIFICATION AND HABITAT. 

The Animal Kingdom is divided into several sub-kingdoms. 
One of these is called Worms (Vermes). This sub-kingdom is 
separated into classes, one of which is named Round Worms 
(N emathelminths). Another division into orders is made, among 
which are the Nematode Worms (Nematodes). This order con- 
tains, among other genera, that of Syngamus, which is repre- 
sented by two species, Syngamus bronchialis and Syngamus 
trachcalis, the last of which is the subject of our present work.* 

Another name for this worm is Sclerostoma, or Strongylus 
syngamus. Syngamus trachcalis is stated to have been found in 
the trachea of the turkey, domestic fowl, pheasant, partridge, 
black stork, magpie, hooded crow, green woodpecker and star- 
ling. I have, myself, found it in the robin, and believe most if 
not all worm-eating birds serve as a host for this parasite. 

HISTORICAL REFERENCE. 
The first public record of the Gapes was made by Dr. Wiesen- 
thall, Professor of Anatomy at Baltimore, Md. In a communica- 
tion dated May 21st, 1797, and published in the Medical and 
Physical Journal in 1799, he says: "There is a disease prevalent 
among the gallinaceous poultry in this country called the gapes, 
which destroys eight-tenths of our fowls in many parts, and is 
most prevalent among young turkeys and chickens bred upon 
established farms. Chicks and poults, in a few days after they 
are hatched, are frequently found to open wide their mouths 
and gasp for breath, at the same time sneezing and attempting 
to swallow. At first the affection is slight, but gradually becomes 
more and more oppressive, and ultimately destroys; very few 
recover; they languish, grow dispirited, droop and die. It is 
generally known that these symptoms are occasioned by worms 
in the trachea. I have seen the whole windpipe completely filled 
with these worms, and have been astonished at the animal's being 
capable of respiration under such circumstances." The above 
is a truthful description of the disease as it prevails in this coun- 
try to-day. In 1808, Mr. George Montagu gave an account to 
the Wernerian Society of a species of Fasciola, which infests 
the trachea of poultry, with a mode of cure. This led to its being 
noticed in the systematic works of the day. Dr. Cobbold, from 

*The name of the genus Syngamus is derived from two Greek words, a u v, wilh, together, 
and y auos, marriage, and has reference to the peculiar union of the sexes. 



whose work on parasites this brief history was taken, has made 
some observations on this worm. In 1879, Lord Walsingham, 
of England, offered a prize of two hundred and fifty dollars, to 
be awarded by the Council of the Entomological Society of Lon- 
don, for the best essay, comprising a complete life history of 
the parasite causing the gapes. Mr. Charles Black and Dr. 
Pierre Megnin, a well-known French scientist, competed for the 
prize. The latter received the award. The conclusions at which 
he arrived in regard to the propagation of the disease are as fol- 
lows: First, that birds pick up mature Syngami filled with eggs, 
which are coughed out by those having the disease, or the eggs 
are taken in their food, or the embryos after they are hatched in 
water, and they are developed within them to the perfect form. 
Second, that no intermediate host, as perfect insects, larvae, mol- 
lusks, or any other living agent, has any share in spreading the 
disease. In a supplement to the above, after discovering a 
nymph of Syngamus in the pulmonary tissue of a red partridge, 
he says: "In the preceding memoir, written about twenty months 
ago, we pointed out that the eggs ejected during the coughing 
fits hatch in the water, and that the embryo, resembling an 
anguillula, may live in this medium for many months, because 
we have kept some alive almost a year, in a low temperature. 
The birds are infected by drinking the water containing these 
embryos. But how are they developed in the body of birds, 
and in what way do they reach the trachea, where they are found 
in the adult stage, fixed to the mucous membrane, like leeches, 
the two sexes united in a permanent manner, and the females 
crowded with eggs?" He closes the supplement as follows: 
"This discovery of the nymph enables us to say that all the 
developmental phases of Syngamus trachealis are now known. 
The only two media which this parasite inhabits during its entire 
existence are the water or moist earth during its embryonal con- 
dition, and the respiratory organs of its victim during its nymphal 
and its adult phase. It is developed without the aid of any other 
medium than the water, corresponding in this respect to the im- 
mense majority of verminous parasites." This, then, is the con- 
clusion at which Dr. Megnin arrives, after five or six years' study 
of the gapes in the various pheasantries of Central France, and 
around Paris. Dr. Cobbold says, in his work on "Parasites," 
page 445: "A change of hosts is probably necessary, but in the 
first instance they either enter the substance of fungi or other 



vegetable matters, or they bury themselves in the soil a short 
distance from the surface." In Lord Walsingham's preface to 
the essay by Dr. M'egnin, he says: "By Dr. Megnin's permis- 
sion, his memoir is now published in a separate form, the sub- 
ject of it being one which could not rightly be included amongst 
the publications of the Entomological Society, although at the 
time of offering the prize I was led, by information gathered from 
various sources, to think it possible that the larvae of some insect 
acted the part of host to the embryonic form of Syngamus" Dr. 
Joseph Leidy believed the embryos would be found in some in- 
termediate host. The above comprised our knowledge on the 
subject when this research was begun. 

PRESENT INVESTIGATION. 

The present investigation was commenced during the summer 
of 1883. Great numbers of young poultry dying of the gapes, 
some of my neighbors applied to me for aid to arrest the disease. 
Knowing very little about the gapes, but having heard it was 
caused by worms in the trachea, I made a careful examination 
of their windpipes, and found numbers of the worms attached 
thereto by their sucker-like mouths. Never having studied the 
Entozoa, and having no works on them, I sent a specimen to 
Dr. Joseph Leidy, of Philadelphia, asking him its name, and 
where I would find information on the subject. He kindly re- 
plied, and referred me to Dr. Cobbold on "Parasites," and an 
article by Dr. N. H. Paaren, in the American Entomologist, Vol. 
2, page 149. I immediately procured these, and reading the ar- 
ticles oh that subject, could find nothing regarding its origin. 
I therefore again addressed Dr. Leidy, asking him for the de- 
sired information. On August 15th, 1883, I received his reply 
as follows: "The source of the gape worm (Syngamus trachealis), 
of chickens, has not been discovered. If you have an opportunity 
of investigating and determining its origin, you may do much 
service to science. It would be found only in the embryonic 
or larval condition, in some intermediate host." I thought this 
was not only a good field for microscopic examination, but also 
one which, should I succeed in the work, would be productive 
of much good. Therefore, I commenced an investigation of the 
coops and their vicinity, where the chicks suffered most from the 
gapes. About these I found three not improbable sources of the 
disease: First, the common earth worm (Lumbricus terrestris): 



second, the sow bug (Oniscus asellus); third, the garden slug 
Limax flavus). My attention was especially directed to one coop 
where the chicks all had the gapes. This was placed on a grassy 
plot, but close by its side was a small space of bare ground, a 
few inches square. It seemed quite probable that here was the 
place where they obtained the parasite, so I dug into it and found 
it full of earthworms. I took some of these home and exam- 
ined them with the microscope, as I did also Oniscus and Limax. 
I found that both the slug and earthworm contained various 
kinds of parasites in abundance. None were found in Oniscus. 
To determine which one, if any of these, was the intermediate 
host of Syngamus trachcalis, I procured some young chicks from 
a neighborhood where no gapes existed, and fed each separately 
to the chicks. In neither of the chicks fed with sow bugs or 
slugs was any result produced, but the chick fed with earth- 
worms developed symptoms of the gapes. To guard against 
error, all the chicks were kept in a barn where they had no access 
to the ground, and their food was cornmeal mixed with pure 
water. 

EXPERIMENTS IN FEEDING EARTHWORMS. 
Exp. i. On September 29th, 1883, at 8:30 a. m., a marked 
chick, about one week old, was fed ten earthworms from the bare 
spot of ground by the side of the coop where the chicks had 
the gapes. The worms were carefully washed in water to re- 
move all the dirt adhering to them, which might contain the 
eggs or embryos of Syngamus. On October 6th, at 7:30 a. m., 
six^days and twenty-three hours after the feeding, I observed the 
first symptoms of the gapes. On October 7th, at 10:30 a. m., 
eight days and two hours after feeding the chick, and twenty- 
seven hours after the first symptoms of the disease, I killed it and 
found twenty-six gape worms. Of these worms, two only were 
found in the trachea; they were at its upper part, and were the 
largest. Ten or twelve of them were in the pharynx. The re- 
mainder were in the esophagus, from its upper part half way 
down to the crop. All these were united in pairs, except one 
male and female. 

Exp. 2. On October 9th, at 8 a. m., another chick, a little 
over two weeks old, was fed four earthworms from the same 
place, with like precautions. At the same time of day on the 
10th 'it was fed six worms. On the nth, 12th, 13th, 14th and 



IO 

15th it was fed ten worms daily. At the same time from the first 
feeding, a little less than seven days, it had the gapes. It was 
killed in eight days and twelve gape worms found, all in the 
trachea. 

Exp. 3. November 13th three chicks, two days old, were fed 
earth worms from my garden, eight, nine and ten days, respect- 
ively. No symptoms of the gapes were produced, but to deter- 
mine positively, the one fed nine days was killed, and no gape 
worms found. This experiment shows that all earthworms do 
not contain the embryo of Syngamus. To confirm this, earth- 
worms from the same place have been repeatedly examined with 
the microscope, and none of the embryos found. 

Exp. 4. Two mature Syngami were broken in pieces, so as 
to free the eggs. They were then placed on the surface of a dish 
filled with dirt, well moistened with water. After two weeks 
some earthworms were placed in this dish and allowed to remain 
ten days. Three of these were fed to a chick, which was care- 
fully watched for two weeks. No symptoms of gapes were dis- 
covered. Evidently the embryos had not obtained access to 
the earthworms in sufficient numbers to produce the disease in 
chicks. 

Exps. 5 and 6. On December 13th, two chicks, four weeks 
and four days old, were each fed six earthworms from the infected 
spot, with the same precautions as before. On the 14th, 15th 
and 1 6th the feeding of six worms was repeated, making twenty- 
four to each chick. On December 20th, about seven days, as 
before, they had the first symptoms of the gapes. One was now 
killed, and twenty-two Syngami were found. On December 
24th, eleven days from the first feeding, the other was killed, and 
sixteen found. All of them were united, and in the trachea. 
None were found in the lungs, but it is probable they were there, 
and want of experience in the search prevented their discovery. 

Exps. 7, 8 and 9. On April 21st, 1884, fed three chicks, two 
days old, each five worms from the same place where the others 
were obtained. Repeated the feeding on April 22d, 23d, 24th, 
25th, 26th and 27th. On April 28th, about seven days from the 
first feeding, all had the gapes. One was now killed and Syngami 
found in the trachea, also three pairs in the lower part of the left 
lung and one pair in the lower part of the right lung. Continued 
to feed the two remaining chicks earthworms until May 5th, just 
two weeks from the first feeding, when one was killed and the 



II 

lower part of the trachea found crowded with Syngami. One of 
these measured seven-eighths of an inch in length, and two or 
three others three-fourths of an inch. They contained fully de- 
veloped eggs, as did also the excretions of the chick just before 
it was killed. This proves that the embryo of Syngamus in the 
earthworm is developed to maturity in two weeks from the time 
it obtains entrance to the chick. The last chick was killed seven- 
teen days from the first feeding, when in articido mortis. In the 
lungs of each of those killed at fourteen and seventeen days from 
the first feeding, embryo Syngami were found in various stages 
of development. 

Exp. 10. On July 16th, fed a chick ten earthworms, and re- 
peated the feeding for nine successive days. The gapes observed 
on the seventh day, as usual. On July 26th, ten days from the 
first feeding, I killed this chick and found a large number of 
Syngami in the trachea, and also the embryos in different stages 
of growth in the lungs. 

Exp. 11. In order to see if Dr. Megnin's theory was correct, 
that the eggs would develop within the fowl, I fed a chick about 
three weeks old, on July 29th, three perfect Syngami, containing 
many thousands of eggs. This chick was carefully watched for 
five weeks, and no symptoms of gapes observed. That this re- 
sult is correct, we have additional proof in exp. 8, in which large 
numbers of perfect eggs were found in the excretions of the 
chick, on the fourteenth day after feeding earthworms containing 
the embryos of the gape worm. I believe however, if the eggs 
should in any manner be retained so as to hatch before they 
passed into the proventriculus,* the gapes would be produced, 
but think such a case must be very rare, and would be unlikely 
to occur unless the embryos were fully developed in the egg be- 
fore they were taken by the fowl. 

Exp. 12. Three young robins (Turdus migratorius), in the 
nest, were fed several infested earthworms each, daily for twelve 
days. These earthworms were taken from the same place as 
those given the chicks. No well marked symptoms of the gapes 
were observed. Two of them were killed, and three or four gape 
worms found in the trachea of each. A number were also found 
in process of development in the lungs. These birds live almost 
entirely on earthworms during a part of the year, and I wished 

*The proventriculus is the first or glandular stomach where the gastric juice is secreted, 
the gizzard being the muscular stomach where the food is triturated. 



12 

to know whether they would serve as a host for the parasite, and 
thus be instrumental in spreading the disease from farm to farm. 
The trachea of robins differs, in its size and anatomical structure, 
from that of poultry, especially at its lower part, where the last 
ring dilates and forms a second larynx. Syngami generally col- 
lect from the lower part of the trachea to its middle, and the 
gapes is simply the effort of the bird to obtain more air through 
this passage, which is obstructed by these worms. It is evident, 
therefore, that birds which have a larger trachea would harbor 
a greater number of Syngami without suffering from the gapes. 
We see this is the case in chicks after they are several weeks 
old, for Syngami can often be seen in their windpipes by open- 
ing their mouths and straightening out their necks. Several 
worms can thus be seen in large chicks, with very little embar- 
rassment to respiration. It is also not improbable that, although 
the embryos may penetrate the esophagus, pass to the lungs and 
thence to the trachea, the greater part may be coughed up and 
swallowed before they are able to obtain a hold on its mucous 
membrane. We know from an examination of chicks that very 
many of them are thrown off in this way. 

Exp. 13. On July 4th, at 5 p. m., fed a chick, about four 
weeks old, a large number of Syngami, just hatched, by turning 
the water containing them down its throat. On July nth, at 7 
p. m., this chick commenced to have the cough or sneeze char- 
acteristic of the gapes. July 12th, coughed much more. On 
July 13th, at 9 a. m., eight days and sixteen hours after the feed- 
ing, I killed this chick and found one single and twenty-nine 
pairs of Syngami. 

Exp. 14. On August 14th, at 7 p. m., fed a young robin, just 
from the nest, a large number of embryo Syngami, hatched in 
water, as in the preceding experiment. It was kept in a cage 
hanging under a tree, and fed by the old bird. August 22d, 
morning: Robin had some symptoms of the gapes, such as rapid 
breathing, an occasional gape and shake of the head, and was 
inclined to sit on its perch, instead of standing up, as usual. 
August 23d : Breathed more rapidly, and evidently quite ill. Au- 
gust 26th: Robin continued to grow weaker and breathed more 
rapidly, and at times gaped, but the gaping was not as promi- 
nent a symptom as in the case of chicks. The robin died the 
morning of the 29th, the fifteenth day from the feeding. On 
examination three fair sized Syngami were found in the trachea, 



13 

not enough to fill it up, so as to produce much gaping. The 
rapid breathing, which was the most prominent symptom, was 
readily accounted for by extensive deposits in both lungs, more 
especially the right. The lower part of each lung was affected, 
and the diseased condition doubtless resulted from the irritation 
of the parasites.* Many other feeding experiments with chicks, 
have been made in different years since the above. All of them 
thoroughly confirm the foregoing ones in every respect, and it 
is deemed unnecessary to detail them here. Experiment 13 
proves that the embryo of Syngamus does not have to pass 
through an intermediate host to obtain any change in structure, 
or increase in development, that the earthworm is simply a 
bearer, in which it lives in its embryonic condition, and through 
which it obtains access to its final host, the fowl. This chick 
was kept in the barn and all other sources of the disease excluded, 
which was not the case with the robin. The time from the feed- 
ing to the production of the disease in the chick was the same 
as when earthworms were fed, which is good evidence that it is 
the embryo instead of the egg in those which causes the disease. 
It may further be stated that in the examination of many infested 
earthworms I never yet found one to contain the eggs of Syn- 
gamus. In dissecting the robin I found an embryo just emer- 
ged from the esophagus into the lung. It was a short distance 
above the proventriculus, was sexually developed, being a male, 
and thus affords convincing proof that they enter the lung this 
• way. In a chick I also found a pair of Syn garni just united, on 
the posterior part of the esophagus, which had the appearance of 
having been penetrated by these worms. I have also found the 
embryo lying beneath the mucous membrane of the esophagus. 

ARTIFICIAL CULTURE. 

Exp. 15. On September 23d, 1883, a mature Syngamus filled 
with eggs was placed in a small glass dish with a little water, for 
the purpose of observing the development of the embryo, the 
structure of the young worms and the time required for them to 
hatch. We also thought that by comparison in this way they 
could be more positively identified in the earthworm. The dish 

•This condition resulting from parasites is mentioned by Dr. . N. II. Paaren. in the 
American Entomologist, Vol. 2. page 149; also by Dr. George M Sternberg from M 
Larrlaine, in an article on the "Production of Tuberculosis by Inoculation, in the 
American' Journal of Medical Sciences, Vol. LXXXIX, page 18. 



14 

was kept covered in a warm room (65 ° to 70 Fahr.), and occa- 
sionally placed several hours in the sun. On October 14th, three 
weeks from placing them in water, they commenced to hatch. 

Exp. 16. June nth, 1885, placed two mature Syngami in a 
small glass dish of water, and kept them in a room where they 
were not exposed to the direct rays of the sun. On June 28th, 
seventeen days from the time they were placed in water, they 
commenced to hatch. 

As will be seen from the above experiments, the time required 
for the eggs to hatch varies under different circumstances. When 
they have been mature for several days and kept moist and in a 
moderately warm place they will undergo segmentation and the 
embryo commence to form. If these eggs are now placed in 
water in a warm place it will take but a short time for the em- 
bryos to hatch. Again, eggs kept in moderately warm water 
will mature their embryos much quicker than those kept cooler. 

.Exp. 17. December 1st, 1884, placed several embryos found 
coiled up in the muscular sac of the segmental organs of the 
earthworm,, in a small glass dish of water and kept them loosely 
covered, in a warm room. These embryos were thought in the 
beginning of the investigation to be those of Syngamus, and this 
method was adopted to see if any growth or development of 
structure would take place in water, whereby we might decide 
the question. In from five to seven days they grew to many 
times their original length, and were developed into male and 
female. A small number of eggs were also seen in different 
stages, within the oviducts and scattered about the bottom of 
the vessel. These worms correspond with the description and 
figures in the Micrographic Dictionary under the head of Anguil- 
lulidiae, and are thus excluded from being the embryos of Syn- 
gamus. 

Exp. 18. Several embryos taken from the intestinal canal of 
the earthworm, where they were found surrounded by mucus, 
were placed in a glass dish of water and kept, as in the fore- 
going experiment, seven days. These embryos, after a few 
hours, coiled themselves vp at the bottom of the dish, and for 
the most part of the time remained in this condition, occasionally 
uncoiling and moving about a short distance. No growth or 
development of structure took place. These embryos correspond 
in size and structure with those hatched from the eggs of Syn- 



15 

gamiis, and later in the investigation were fully identified as being 
the same. 

Exp. 19. Placed several embryos from the intestinal canal of 
the earthworm, like those in the preceding experiment, in a cov- 
ered glass dish of water, and then in an incubator, and kept them 
at 105 Fahrenheit for seven days, at which time they were alive, 
but no change of structure or development had taken place. 

Exp. 20. One' pint of blood from a calf was allowed to stand 
in a glass fruit jar until the solid portion had settled, leaving the 
serum at the top. On May 5th, at 9 a. m., one dram of this 
serum was placed in a Syracuse solid watch glass, with ground 
edges, containing twenty of the last described embryos. These 
embryos had been kept in the watch glass in water one week, 
and were nearly all lying quietly coiled up about its center. The 
most of the water was removed by a pipette before the serum 
was added. As soon as this was clone the embryos uncoiled 
and became quite lively, as though they had at last found their 
natural element. The watch glass was placed in an incubator, 
covered by another one with ground edges, but leaving a small 
space for air. The temperature had previously been regulated 
so as to remain at 105 Fahr. At 9 p. m., on examining them 
with the microscope, they had slightly increased in size and were 
commencing to moult. On May 6th, at 9 a. m., they were again 
taken from the incubator and examined, when the process of 
moulting had still further advanced. At 4 p. m. I found them 
all dead. The culture fluid had become putrid. 

Exp. 21. May 7th, 4 p. m., completely satisfied that I was 
on the right track, I removed four more embryos from an earth- 
worm and placed them in another portion of serum, and in the 
incubator as before. On May 8th, at 9 a. m., removed them to 
another watch glass containing fresh serum, by taking them up 
under an inch objective with a small splinter of wood whittled 
to a fine point. At 9 p. m. the same day they were again removed 
to fresh serum. One was found dead, another had moulted, and 
the two others had nearly completed that process. May 9th, 9 
a. m., they were seen to have increased in size, and were removed 
to another portion of serum. These embryos lived between four 
and five days in the incubator, and were about moulting the second 
time. They were sufficiently developed to show the peculiar 
structure of the mouth of Syngamus trachcalis. One of them 



i6 

measured .0139 inch in length, and the exuvia, in which it still 
remained, .0227 of an inch. (See figure 3.) 

Exp. 22. Four of the embryos from the earthworm were 
placed in one dram of egg albumen, after it was beaten to render 
it fluid. They were placed in the incubator as before, and 
changed to fresh albumen daily. After being kept in this way 
six and one-half days, they were alive, but there was no change 
in their structure or size, or any appearance of moulting percept- 
ible. Evidently the proper food for their metamorphosis and 
growth was not contained in this fluid. In these culture exper- 
iments the incubator used was one in which the heat could not 
be thoroughly controlled. It is believed with a good one and 
more experience better results could be attained. It is also 
thought the blood serum of a fowl would be best adapted for 
this purpose. This method of artificial culture of animal parasites 
is believed to be new, and if varied according to the different 
circumstances in which they are found in nature will, we think, 
render easy the solution of some of the most difficult questions 
as to the life history and embryonic forms of many of these 
creatures. The subject is of great importance, for large num- 
bers of both human beings and animals perish each year through 
their agency. Moreover, it is not far removed from that great 
question which occupies so prominent a position before the 
medica] profession at the present time. I refer to the germ the- 
ory of disease. The one is an animal, the other a vegetable par- 
asite. The method of artificial culture is now being used for 
working out the latter; I see no reason why it cannot be success- 
ful in the former. 

EMBRYOLOGY AND DEVELOPMENT OF SYNGAMUS. 

The egg is formed out of the granular material seen near the 
extremity of the ovarian tubes. It is shaped into small round 
bodies which pass down towards the uterus, within the horns of 
which they are supposed to become impregnated, and receive the 
hard external coat called the shell. Within the body of the female 
Syngamus, about fourteen days after its entrance into the fowl, 
are found several thousand eggs in various stages of develop- 
ment, from the granular material of which they are formed, as 
it exists in the ovaries and ovarian tubes, to the perfect egg in 
the uterus. The perfect egg is oval, about .004 inch in its long, 



17 

and .0025 inch in its short diameter. At each end is a valve or 
lid which drops off when the embryo emerges from the egg. It 
has been the general opinion among naturalists that the mature 
eggs of Syngamus were never discharged through their natural 
outlet during the life of the female, that being rendered impos- 
sible by the intimate union of the genital orgajns of the sexes, 
whereby the outlet of the vagina was completely closed. They 
believed that only at the death of the worm and disintegration 
of its body were the eggs set free. That such is not the case 
in some instances, / know, for I have distinctly seen, under the 
microscope, with a power of fifty diameters, the eggs pass out at 
the posterior part of this union in a living pair, just removed 
from the trachea of a chick. Two or three eggs were discharged 
at regular intervals, each minute. On close observation there 
was clearly observed movements of the worm, showing the nat- 
ural expulsive efforts, followed by the extrusion of the eggs. 
Now, in about fourteen days after the feeding of earthworms con- 
taining the embryos of Syngamus, we have, in several later exper- 
iments, some of which are not herein recorded, observed the per- 
fect eggs of Syngamus in the excretions of the chicks. These 
chicks were then killed and the living pairs of Syngami found 
attached to the mucous membrane of the trachea. Some of 
these pairs had not yet attained their complete growth, yet the 
eggs, near the genital outlet, were fully developed. None of 
them were found dead and their bodies breaking up in the 
trachea. From these observations we have no doubt that the 
living worm, contrary to the opinion heretofore entertained, does, 
during its life, extrude a large number of perfect eggs, but al- 
ways dies while many yet remain in its body, which are set free 
when that decomposes. I have never been able to press the eggs 
out through the vagina in a dead Syngamus. This may be one 
reason why naturalists have thought they did not pass out when 
living that way, but I believe all dead animals have their genital 
passages contracted in the same manner. It has also been the 
general opinion that the eggs furthest advanced in a mature 
Syngamus while living and just removed from the trachea of a 
fowl contain the perfect embryo already moving actively about 
within the shell. That such is not the case we believe and will 
briefly give our reasons for this opinion. In experiment No. 8, 
it will be seen that a chick fed earthworms containing the em- 
bryos of Syngamus developed the gapes, and in fourteen days 



i8 

from the time of the first feeding great numbers of the eggs of 
Syngamus were found after they had passed through the fowl's 
intestines. These eggs passed from perfect worms, which were 
found attached to the trachea of the chick, killed the same day. 
Now, the eggs which passed through the chick, and those found 
about the perfect worms in the trachea, showed no sign of em- 
bryonic formation. Moreover, we will say that after the exam- 
ination of many perfect worms removed from the trachea, we 
have never found the embryo developed within a single egg at 
that time. In our experience, it takes these eggs not far from 
three weeks, varying somewhat with the temperature, to mature 
and bring forth their embryos. We believe Syngami, in which 
active embryos wera found within the egg, had been for many 
days mature, and probably kept in a moist condition, either 
within the body of the bird or external to the same. The em- 
bryo of the lung worm of calves (Strongylus micrurus), is fully 
developed in the egg while in the lungs of the calf. Possibly, 
reasoning by analogy has had something to do with this opinion 
heretofore entertained concerning Syngamus. It is evident the 
eggs, scattered over the ground in the natural way, hatch much 
quicker during the hot months of summer than later in the sea- 
son. Indeed, it is quite probable that most of these last perish 
on account of the cold, without the formation of an embryo. 

DEVELOPMENT OF THE EMBRYO. 

The process of development from the egg is as follows:. 
The yolk undergoes segmentation; that is, becomes divided into 
2, 4, 8, etc., round masses or spheres, this division being con- 
tinued until it assumes the mulberry state. The embryo is devel- 
oped from this around the inner part of the shell, in the form 
of a circle. Before it emerges the embryo usually coils itself 
within the egg, like the figure 8, from which it generally comes 
out head first. The time required for the perfect egg to pass 
through the different stages, until the embryo issues from it 
varies, as heretofore stated. On one occasion a few of the em- 
bryos came forth in seventeen days. The embryo on emerging 
resembles an Anguillula, but its movements are not as rapid as 
most of the worms belonging to this order. It is about .on inch 
in length, and .0005 inch in width at its middle. The posterior 
half of the body is filled with a fine granular matter. After the 



19 

embryos have been in water a few days they moult, losing about 
.0005 inch in length; their tails are then more blunt. Sometimes 
they pass through the first moult while coming out of the egg, 
leaving the old skin within. 

THE EMBRYO IN THE EARTHWORM. 

After many careful microscopic examinations of the embryo, 
as found in the earthworm, I have arrived at the conclusion that 
it does not differ in its structure, so far as can be discovered, from 
the embryo which has passed through one moult, after the egg 
has hatched in water. The method of finding them in the earth- 
worm is as follows: Select a poultry yard where chicks have had 
the gapes for several years, so that the earthworms may have 
plenty of the parasites. From near the surface of bare spots of 
ground, which chicks with the gapes have frequented, take some 
of the earthworms and examine them with the microscope. The 
following method is recommended: Throw the earthworm to be 
examined into a solution of common salt (chloride of sodium), 
having the strength of about two ounces to the pint of water. 
When it ceases to move, rinse in pure water; then, with sharp- 
pointed scissors, slit the worm its entire length. Spread out on 
each side, to expose the alimentary canal. In order to intelli- 
gently proceed, we will briefly describe the organs contained 
therein. They consist of the mouth, pharynx, esophagus, crop, 
gizzard and intestine. Directly connected with the esophagus, 
about its middle and posterior part, are found six white bodies, 
three on each side called the esophageal or calciferous glands. 
The esophagus passes directly into the crop, which is just in front 
of the gizzard. Following this is the intestine, which passes 
through the remaining portion of the worm. We cut off the in- 
testine, just back of the gizzard, and taking small pieces, about 
one-eighth inch long, place them on a watch glass with a little 
water, pick them well in pieces, and examine carefully with an 
inch objective. We generally find the embryos a short distance 
below the gizzard, not often more than half way to the tail. There 
are numerous kinds of parasites which inhabit the earthworm, 
some of them numbering thousands in a single worm. We have 
also found the earthworms in different localities to harbor very 
different kinds of parasites. The method of distinguishing the 
embryo of Syngamns is its size, description as here given, and 



20 

general appearance as seen in the engravings. We believe it is 
taken in by the earthworm with its food, and passes down into 
the intestine, where it remains until transferred within its host to 
the digestive organs of some bird, or after a time passes through 
into the soil and perishes. T.his method of taking in the embryo 
by the earthworm is the common law in nature, through which all 
creatures, man included, obtain their intestinal parasites. 

THE EMBRYO OF SYNGAMUS IN THE FOWL. 

The embryo passes into the crop within the intestine of the 
earthworm. We wish to determine at what point it leaves the 
digestive canal and passes into the lungs and trachea of the chick. 
We have never been able to trace the embryo below the esopha- 
gus, after many examinations of chicks dead of the gapes. If we 
admit that they do not pass through the proventriculus and giz- 
zard alive, which I have no doubt is the truth, there are only two 
organs, the crop and esophagus, through which they could gain 
admission to the lungs. The crop is simply a dilatation of the 
esophageal structures, and acts as a reservoir for the food. We 
believe the embryo passes through the esophagus just above the 
proventriculus, for the following reasons: The distance to the 
lung structures is very short, only the thin wall of the esophagus 
intervening. The orifices of the lenticular glands of the esopha- 
gus are of greater diameter than the embryo, so it could readily 
enter through them. That it does so we believe, for we have 
found them beneath its mucous membrane. The pulmonary 
bronchi ramify over the outer surface of the esophagus, through 
the substance of which there are numerous tubular structures, 
which, it is not improbable, may be connected with them. We 
have seen the embryo just emerged from the esophagus into the 
lung, and have in all the chicks carefully examined for that pur- 
pose, after dying of the gapes, found several echymosed spots, 
which looked as though the embryos had passed through. We 
have also found them recently united on the outer wall of the 
esophagus, one pair being the smallest we ever saw. In dissecting 
chickens dying of the gapes, we have, many times, found the 
esophagus adhering to the lungs, as we believe from the inflam- 
mation caused by the passage of the embryos. This condition of 
echymosis, and adhesion of the esophagus to the lungs, we have 
never found in any chicks we have dissected which did not have 



21 

the gapes. Both male and female embryos do not develop beyond 
a certain point until union takes place. After this they pass up 
into the trachea, where they attach themselves to the mucous 
membrane 'and attain maturity. 

ANATOMICAL DESCRIPTION. 

We shall not attempt any extended anatomical description of 
Syngamus trachectlis. The illustrations accompanying this investi- 
gation will show its appearance in the different stages of its ex- 
istence. We will briefly say that the mouth in this Genus is large, 
circular, and surrounded by four outer membranous and six inner 
chitinous lips. The young worm has eight inner lips, two of 
which uniting with two others, reduces the number to six in the 
adult worm. Within it is hollowed out, and contains around the 
opening to the digestive apparatus, eight lance-like organs, which 
are supposed to pierce the mucous membrane for extracting the 
blood of its host. 

THE MALE. 

The male has been found coupled on the external wall of the 
esophagus of the chick when .035 inch long, and .002 inch wide. 
At maturity it attains the length of about .24 inch, and a breadth 
of about .02 inch. The diameter of the head exceeds that of the 
body, which is round, and its posterior part, containing the genital 
organs and anus, is united to the anterior part of the vulva of the 
female by a membranous hood-like organ, called the caudal 
pouch. This organ is elongated in front, with about one-third 
of its diameter cut out on its posterior part, where it is free from 
the female. It is supported by eight principal ribs, which are sub- 
divided as follows : The posterior ribs on either side are double ; 
next to these on each side they are trifid, followed by a single rib, 
between which are the two anterior ribs, also trifid. These divi- 
sions of the ribs, eighteen in number, each have at their extremity, 
which reaches to the circumference of the caudal pouch, a disk 
or sucker, by means of which the male attaches itself to the genital 
organs of the female and maintains so strong a hold, that even 
after death they are separated with much difficulty. There is no 
actual growing together of the organs, as has been the commonly 
received opinion, for they can be separated entire by careful 
manipulation in diluted glycerine. Within is seen the digestive 
and internal genital organs. 



22 

THE FEMALE. 

The female has been found united with the male on the 
esophagus when .055 inch long and .0025 inch in width, and in its 
adult state sometimes measures .875 inch in length, by nearly 
.045 in width. It is of a bright red color from the absorption of 
the hematin of the blood upon which it lives. When mature it is 
irregularly cylindrical, curved, and often variegated by the white 
winding uterine horns filled with eggs. The tail is conical and 
just in front of its extremity is the anus. The vulva is a short 
distance back of the head and is attached at its anterior part to 
the caudal extremity of the male. At its posterior part this union 
is incomplete, the perfect eggs passing out here through the 
vagina. The digestive and genital organs can be traced within. 

PREVENTION OF THE GAPES. 

The very best results which can be attained from the study of 
disease is its prevention. If the only way in nature by which fowls 
contract the gapes is from eating earthworms containing the 
embryos of Syngamus, it follows if none of these were eaten the 
disease would become extinct. We believe, after many years' 
study of the gapes, that this is the only natural way in which 
fowls contract the disease, but, should they take in the embryos 
in any other way the disease would be equally liable to occur. We 
have never observed this to take place, and believe it never docs 
except through the instrumentality of man. Adopting this view, 
there are two methods of prevention, either one of which will 
prove effectual. First, keep young fowls from the ground where 
earthworms are infested by the embryos. Second, destroy the earth- 
worms containing them, when the fowls could be allowed their 
liberty. We had thought a third method nrght be added, namely, 
to mix with the bird's food some anthelmintic, which, if worms 
containing the embryos were eaten, would destroy them without 
injuring the fowl. This opinion was changed after the experi- 
ments detailed belowwere concluded. The first method consists in 
either keeping them on wooden floors, or some grassy plot or 
ground where the disease has never existed. The second method, 
that of destroying the earthworm, involves the question as to 
what is the best method of doing this. The article to be chosen 
must be cheap, effective, readily applied, and safe to use. We 
have experimented with three different substances, each of which 



23 

possesses to a considerable degree these qualities. They are 
•common salt (chloride of sodium), lime (oxide of calcium), and 
wood ashes (mostly composed of potassa and its carbonate). In 
the experiments medium-sized earthworms were used, and the 
'embryos of Syngamns were taken from the intestine of the earth- 
worm. 

EXPERIMENTS WITH EARTHWORMS AND EMBRYOS 
OF SYNGAMUS. 

Exp. i. An earthworm just dug, and with the dirt still adher- 
ing to it, was thrown into dry lime which had been slacked for 
several weeks. At the end of twelve minutes it was dead. 

Exp. 2. Another earthworm was thrown into lime water; in 
seven minutes it ceased to move. 

Exp. 3. An embryo of Syngamiis trachealis was placed in lime 
water ; it was observed for two hours, at the end of which time it 
was still alive and active. 

Exp. 4. An earthworm was placed in a solution of common 
salt having the strength of one-fourth pound to the gallon of 
water. In six minutes it was dead. 

Exp. 5. An embryo of Syngamiis placed in the above solu- 
tion lived thirty-three minutes. 

Exp. 6. An earthworm placed in a solution of salt having the 
strength of one-half pound to the gallon of water lived four 
minutes. 

Exp. 7. An embryo of Syngamiis placed in the above solu- 
tion ceased to move in fourteen and one-half minutes. 

Exp. 8. An earthworm placed in a salt solution having the 
strength of one pound to one gallon of water lived about three 
minutes. 

Exp. 9. An Embryo of Syngamiis placed in the above solu- 
tion lived three minutes. 

Exp. 10. An earthworm thrown on dry salt ceased to move 
in somewhat less than three minutes. 

Exp. 11. An earthworm thrown on dry ashes lived about 
twelve minutes. 

Exp. 12. An earthworm placed in lye made by pouring warm 
water on wood ashes and letting it stand one hour, the proportion 
being one-half pound of ashes to one gallon of water. The earth- 
worm ceased to move in three minutes. 



24 

Exp. 13. An embryo of Syngamus placed in the above solu- 
tion was apparently unaffected at the end of twelve hours. 

Exp. 14. An embryo of Syngamus placed in a watch glass 
containing- a mixture of water and asafoetida, many small pieces 
of the latter being scattered over the bottom. At the end of one 
hour it was unaffected, although almost constantly in contact 
with the lumps of asafoetida. 

Exp. 15. An embryo of Syngamus placed in a watch glass 
with water, and several small pieces of an onion, making a strong 
solution, were added to the same. At the end of six hours very 
little abatement in the vigor of its movements was perceptible. 
In twelve hours it still lived, but its movements were very slow. 

The result of the above experiments may be stated as follows : 
Lime, salt, and ashes are all effective in destroying the earthworm. 
Lime water and lye of the strength used seemed to have very 
little effect on the embryo of Syngamus. Doubtless, a stronger 
solution of ashes would kill it, and it is probable that lime in 
substance would also be effective. Salt not only destroys the 
earthworm, but it also kills the embryo of Syngamus. The anthel- 
mintic power of asafoetida and the onion has disappointed us 
much. The latter belongs to the same family (Allium), and has 
similar properties to garlic, which has been so highly recom- 
mended as a specific in the gapes. Ashes, lime or salt may then 
be used. The first two can be spread over the ground. Lime, in 
the form of lime water, is exceedingly cheap, but, exposed to> the 
air, or in the soil soon combines with carbonic acid, forming car- 
bonate of lime, which is probably harmless to the earthworm. We 
believe salt is more reliable, and it has also the additional ad- 
vantage of destroying the embryo of the gape worm in the soil. 
It can be used in poultry yards in the proportion of one pound to 
the gallon of water, or, if the soil is very moist, two pounds would 
be better. If a large extent of ground is to be treated, the salt 
could be scattered in substance over the surface and left to be 
dissolved by rain or plowed under, taking care that none of it 
is eaten by fowls. This method has been adopted by some with 
success, no more gapes having developed in their chicks. All 
poultry dying of the gapes should be burned, and not left upon 
the ground, or even buried deep, as advised by some, for the eggs 
may hatch, and the embryos be taken by the earthworm to the 
surface to propagate the disease. 



25 



CONCLUDING REMARKS. 



Before closing, we wish carefully to examine a few points 
concerning the life history of Syngamus trachealis, and the propa- 
gation of the gapes. First, do fowls contract the disease by pick- 
ing up the eggs, or mature Syngami containing them? Dr. 
Megnin's parrot was claimed to have taken the disease from eat- 
ing, on August /th, four mature Syngami filled with eggs. The 
first symptoms of the gapes manifested themselves on August 
28th, twenty-one days after the feeding, and the bird died Sep- 
tember 10th, on the thirteenth day of the disease. We believe if 
the eggs were retained and hatched before they reached the 
proventriculus, the gapes would result. But we think such a case 
is exceptional, and not the way in which the disease generally 
occurs. In proof of this we will not only bring forward the chick 
fed mature Syngami (see feeding exp. 11), but also, the general 
fact that chicks, about fourteen days after they take in the 
embryos of Syngamus, have large quantities of mature eggs pass 
through their intestines into the soil. According to first theory, 
these eggs should hatch within the chick; it would thus become 
self-infecting, and would almost necessarily die. On the con- 
trary, after chicks are a few weeks old they generally recover, 
their windpipes being large so that the usual number does not 
very materially interfere with their respiration. That the eggs are 
not contained in the earthworm and thus taken we believe is true, 
for, in the examination of very many infested earthworms during 
the past fourteen years, we have never found an egg of Syngamus. 
It is also evident that the time required to produce the gapes by 
feeding earthworms is too short for the eggs to hatch and the 
embryos to pass through their different stages. Again, the eggs 
are so small they could not be seen, as they were scattered over 
the ground, and picked up by chicks, and it is highly improbable 
that they would retain their vitality through the long winter 
months in this climate, and propagate the disease in chicks the 
following summer. We are aware that the eggs of various in- 
sects survive the winter, and continue their species from year to 
year, but we have found by experiment that the eggs of Syngamus 
trachealis will not hatch after being kept a few weeks, fatty de- 
generation takes place, and their vitality is destroyed. We con- 
sider it unnecessary to bring forward further proof on this point. 
Dr. Megnin himself abandons the theory, and says: "The birds 
are infected by drinking water containing the embryos." We are 



26 

then forced to the conclusion that the living embryo, in some 
manner, finds its way into birds, and is there developed into the 
perfect worm. That the gapes can be artificially produced by 
feeding the embryos of Syngamus hatched in water to chicks, we 
readily admit, for we have proved such is the case by experiment 
13. But we deny that this is the natural way in which they con- 
tract the disease. In this climate of ours, with a long severe 
winter, the thermometer is often down to zero, water, when re- 
maining on the surface of the ground would be frozen a hundred 
times, and during the warm season none would be found except 
in rainy weather. How then, we ask, would it be possible for 
the embryo to live through the cold season in water, and be taken 
by chicks the next spring, in the water they drink from the sur- 
face of the ground. Some of the Nematoid worms, to which class 
Syngamus belongs, can be brought to maturity by being taken in 
water. Nevertheless they have intermediate hosts which act as a 
bearer, exactly as the earthworm acts as a bearer to the gape worm. 
They differ from most of the tape worms which have to pass 
through an intermediate host, in which they are partially devel- 
oped, to prepare them for a final development in their last host. 
To illustrate: Trichinae belong to the Nematoid worms, the 
same class as the gape worm, and could be propagated in man by 
drinking them in water, but did you ever hear of this taking place 
in nature? No! They get them from their intermediate host, the 
hog. The question is not what might happen, but what does 
actually occur in nature, without the intervention of man. I do 
not believe the Creator, in his infinite wisdom, has designed that 
the gape worm should be without a bearer, for you can easily 
perceive what would become of the poor worm in these Northern 
States were such the case. The soil is often frozen to a great 
depth, and it would be utterly destroyed. Besides this, it could 
not be picked up by a chick or bird, except by the merest acci- 
dent, for it is so small it could not be seen. No! this is not so. 
It has been wisely decreed that the earthworm should be its inter- 
mediate host, in the intestine of which it finds all the nourishment 
necessary to sustain it. When winter comes it is carried deep into 
the ground, out of all reach of cold, and in the spring is brought 
again to the surface ready to be picked up in the earthworm, and 
pass through the remaining portion of its existence in its final 
host, the fowl. Now , the proof is positive, and must be acknowledged, 
that earthworms do contain the embryos of Syngamus trachealis, and 



27 

that the gapes can be produced by -feeding the earthworms containing 
them to chicks (see the various experiments herein detailed). But, 
some say it is only an accidental host of the earthworm, taken 
in with the particles of earth, leaves, etc., while boring through 
the soil, and that the embryos may even be used as food by the 
earthworm. I have not the slightest faith in its being an acci- 
dental host of the earthworm, temporarily taken in with leaves, 
grass, etc., or used as food. If this was the case, why should we 
find it, as I have often done, in many earthworms in an infested 
locality, in midwinter, down deep in the ground, in the same posi- 
tion as in summer, in the intestine of the earthworm? Why did 
it not pass off with leaves and other matter used as food, instead 
of remaining throughout the year? I have found twenty in a 
single earthworm, and often five to ten. If the embryo was taken 
in as an accidental host, I see no reason why we should not at 
times find some of the eggs of Syngamus in the earthworm, but as 
before stated, we have never found one. In all our study of the life 
history of the gape worm,we have never found any way in nature, zvith- 
out the intervention of man, through which they obtained access to birds, 
except the earthworm. There is no food more natural for fowls 
than these. Chicks, two days old, eat them greedily. No embryos 
of Syngamus have ever been discovered, on repeated examinations, 
in any other forms of animal life about the coops of chicks having the 
gapes, except earthworms. These examinations were made with 
the microscope, and also by feeding experiments with chicks. No 
embryos like those of Syngamus, were found in earthworms which 
did not produce the gapes by feeding them to chicks. / have made 
inquiries in various parts of our country, where no earthzvorms are 
found, as to the existence of gapes, and have invariably received the 
reply that their fozvls do not have the disease. The robin and other 
worm-eating birds which act as hosts for Syngamus, without 
question disseminate the disease from one farm or part of the 
country to another. When you remove your chicks to new 
ground where there has never been any gapes, the earthworms 
will not contain the embryos, and your chicks will be free from 
the disease. This has been demonstrated many times in this 
vicinity. Also, the fact that using a strong solution of salt on the 
ground, and thus killing the infested earthworms about coops 
where chicks have previously had the disease, would entirely pre- 
vent any outbreak the following year. It is a matter of common 
observation, that the gapes is more prevalent during wet seasons, 



28 

than dry ones. This is easily explained; the reason being that 
earthworms are more plenty on the surface of the ground, where 
they are easily picked up by chicks. It is also well known that 
when chicks are let out in the early morning, they are more apt 
to have the gapes. This was thought by many to result from their 
getting wet and cold, but it is easily explained by their finding the 
earthworms out at that time, when if they were not let out until 
the moisture was dried off the ground, the earthworms could not 
be found, they had retired into their burrows. The old adage, 
"The early bird catches the worm," well illustrates this point. It 
is also a well-known fact that chicks kept near a chip yard, were 
apt to have the gapes. This is readily explained by reason of 
their easily getting earthworms by scratching the chips from the 
surface of the ground, earthworms being found plenty in such 
places. 

FINALLY, THERE IS NOTHING CONNECTED WITH 
THE GAPES WHICH CANNOT BE FULLY, AND CLEAR- 
LY EXPLAINED THROUGH THE AGENCY OF EARTH- 
WORMS. 

We will' recapitulate the several points we consider established 
by this investigation. First, that the earthworm is the inter- 
mediate host of Syngamns trachcalis, is proved by many successful 
experiments in feeding them to chicks. None of the chicks fed 
earthworms from an infected spot, failed to have the gapes in 
seven days. On microscopic examination, the embryos of 
Syiigamus were found in these earthworms. That no other forms 
of animal life about the coops act as a host for Syiigamus, proved 
by feeding all those found to chicks and they failed to produce 
the gapes; also, none of the embryos were found in them on ex- 
amination with the microscope. That all earthworms do not con- 
tain the embryos of Syiigamus, proved by feeding three chicks 
earthworms from a place where no gapes existed. They failed to 
have the gapes, and no embryos of Syiigamus could be found in 
the earthworms with the microscope. That the earthworm is 
only a bearer, or means of conveying the embryo to the fowl, is 
proved by feeding the embryos hatched from the eggs to a chick, 
and thus producing the gapes. Also, the fact tl*at the embryos 
in the earthworm do not develop, either in growth or structure, 
more than when they emerged from the egg. That the embryo 
of Syiigamus is not an accidental host of the earthworm, proved 
by finding them in considerable numbers, in many earthworms, 



2 9 

in an infected spot, throughout the year. No earthworms, no 
gapes. This view is supported by inquiries made in various parts 
of the country where there are no earthworms, in which places, 
they say the fowls do not have the gapes. The embryo of 
Syngamus has been found in the earthworm, and identified by 
tracing it through its different stages from the earthworm to the 
trachea of the chick, and also by artificial culture. That they pass 
through the esophagus of the chick is demonstrated by finding 
them beneath its mucous membrane, and just after they had 
passed through into the lungs; also, by finding the esophagus 
adherent to the lungs in many chicks which had the gapes, this 
condition not being found in those which did not have this disease. 
That the disease is transmitted from one year to another by drink- 
ing water containing the embryos, is rendered impossible in a cold 
climate, where the water is frozen many times during the winter, 
and often dried from the surface in the summer. That the robin 
(Turdus migratorius), and probably many' other worm-eating 
birds may act as a host for Syngamus, and thus be instrumental 
in spreading the disease, is proved by feeding three robins and 
finding full-grown worms in their tracheas. That the union be- 
tween the genital organs of the male and female is incomplete at 
its posterior part, so that the eggs can be, and are readily ex- 
pelled during the life of the worm, proved, by seeing this take 
place under the microscope. That the mature Syngamus, while 
yet in the trachea of the fowl, lays its eggs, which are coughed up, 
swallowed, and pass through the intestines of the fowl to the 
ground. Proved, by finding the eggs in the excretions, and the 
living worms from which eggs were passing, in the trachea. That 
the genital organs of the sexes are not grown together, proved, 
by separating them without rupture, and finding them to adhere 
by means of suckers on the genital organs of the male. That the 
mature egg does not contain an embryo is proved by examining 
them after they are naturally expelled by Syngamus, and finding 
that two or three weeks are required for the embryo to develop in 
them. That the embryo of Syngamus is but slightly affected by 
the anthelmintics which have been used to prevent and cure the 
disease, as asafoetida and garlic. They cannot be relied on for 
this purpose. Lastly, to prevent your fowls from having the 
gapes, remove them to some spot where the disease has never 
existed, or destroy the infested earthworms in the ground with 
common salt. 



3o 

The life history of Syngamus trachealis is as follows: Earth- 
worms containing the embryos are eaten by the fowl. The 
embryos are liberated from the intestine of the earthworm and 
work their way through the esophagus into the lungs and bronchi. 
Here they pass through the nymph stage and acquire sexual 
maturity. The male and female then unite, work their way into 
the trachea, and attach themselves to its mucous membrane by 
their sucker-like mouths. Between six and seven days are re- 
quired from its entrance into the fowl until its attachment to the 
trachea. In about seven days more the eggs within the body of 
the worm become mature. They are coughed up into the mouth, 
swallowed by the fowl, and pass through it into the soil. In about 
three weeks, the time varying somewhat according to the tem- 
perature, these eggs, exposed to the moisture and sun, hatch; the 
embryos are taken in their food by the earthworm, where they 
remain until picked up by some bird, when the above process is 
repeated. Some years one-half or two-thirds of the young fowls 
in certain localities are destroyed by this disease. This investiga- 
tion proves that if they were kept from eating infested earth- 
worms, that terrible scourge of poultry, the gapes, would be en- 
tirely prevented. Not only this, but it serves as a key to unlock 
the mysteries surrounding several other diseases, caused by para- 
sites belonging to this family; namely, the lung worm of calves 
(Strongylus micrurus), the lung worm of hogs (Strongylus donga- 
tus), the lung worm of sheep (Strongylus filiaria), the grouse 
disease (Strongylus pergracilis). Great numbers of calves, hogs, 
sheep and grouse are yearly destroyed by these parasites. Their 
intermediate hosts have never been discovered. From certain 
inquiries which I have made, I venture to predict that the earth- 
worm will be found to be their intermediate host.* 



*Cobbold in his work on " Parasites," page 336-346, after a series of observations states 
his belief that the earthworm may act as an intermediate host for Strongylus micrurus. 



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